Origin: 1500–10; earlier elrich, equiv. to OE el- foreign, strange, uncanny (see else) + rīce kingdom (see rich); hence “of a strange country, pertaining to the Otherworld”; cf. OE ellende in a foreign land, exiled (c. G Elend penury, distress), Runic Norse alja-markir foreigner
el·dritch (ěl'drĭch) adj. Strange or unearthly; eerie.
[Perhaps Middle English *elriche : Old English el-, strange, other; see al-1 in Indo-European roots + Old English rīce, realm; see reg- in Indo-European roots.]
(ěl'drĭch) 
drɪtʃ